Non-volatile memory devices, such as flash memory devices, are used in many computers and other electronic products to store information. A flash memory device stores information in numerous memory cells, which are usually formed in a semiconductor chip. Each of the memory cells often has a metal-oxide semiconductor (MOS) transistor with two different transistor gates: a control gate and a so-called “floating” gate. The control gate is used to turn the transistor on and off to control access to the memory cell. The floating gate is usually a place where information is stored in each memory cell.
A flash memory device usually has a programming operation to store information into the memory cells, a read operation to retrieve information from the memory cells, and an erase operation to clear information from the memory cells. Programming, read, and erase operations usually involve applying voltages to the control gates of the memory cells and to other device components within the flash memory device. A conventional flash memory device often goes through many programming, read, and erase operations during its life.